For purposes of illustration, the invention will be discussed with reference to a glass panel door, such as used in a refrigerator or freezer in a grocery store or the like. It is to be understood that the term "freezer door" as used herein also includes refrigerator doors. It is to be further understood that the use of the connector is not limited to doors. For example, the invention is also suitable for use in windows for pools, or other areas subjected to wide temperature and moisture conditions.
Glass refrigerator and freezer doors typically are made from two pieces of glass separated by air or other insulating gas. A common problem associated with such glass doors is that moisture condenses on the outside glass owing to warm humid air striking the cold glass. This makes it difficult, if not impossible, for the customers to see what is in the refrigerator or freezer without holding the door open, which results in increased use of electricity for maintaining the desired temperature in the freezer or refrigerator. The prior art method now being used to minimize the condensation is to dispose a conductive element or film on the inside of the front glass, solder leads of a power cable to ends of the element or film and continually heat the outer glass, whether or not the ambient conditions are warm and humid. Additionally, should the glass be broken in the area of the electrical connections, the circuit to the glass remains active, possibly causing a safety hazard.
It is desirable, therefore, to have a system for warming the outer glass that senses when there is moisture on the glass and activated the heating element or film only for a sufficient time to dry the glass. Additionally it is desirable to have a system that will automatically deactivate the heating element if one or the other of the glass layers breaks in the area of the electrical connections to the element or film.